1. Technical Field
The present invention relates to a method for controlling a droplet discharge device and to a droplet discharge device, and specifically relates to a control performed during standby of a droplet discharge head.
2. Related Art
Droplet discharge devices for discharging droplets of a liquid substance (functional liquid) onto a substrate or another surface are known as, for example, means for image drawing or various film-forming means. It is common for droplet discharge devices to discharge a plurality of functional liquids while switching among the liquids in accordance with the discharge target. Since the functional liquids differ in viscosity and other characteristics according to their type, the droplet discharge head is appropriately controlled according to the type of functional liquid so as to obtain the optimal discharge characteristics (see Japanese Laid-Open Patent Application No. 2003-21714, for example).
When this type of droplet discharge device is in a standby mode of not discharging droplets, the vibrating plate of the discharge head is made to undergo microvibration at a much lower amplitude than during droplet discharge in order to prevent the viscosity of the functional liquid in the discharge head from increasing. The frequency of these microvibrations is about several dozen kHz, for example.
When microvibrations are performed during standby of the discharge head, the viscosity increase of the functional liquid in the discharge head can be suppressed, but the behavior of the functional liquid causes the temperature of the discharge head to increase to the saturation temperature at the time of the microvibrations. When the discharge head then transitions from standby mode to drawing mode, the discharge head is cooled by the continuous supply of functional liquid, and the discharge head progressively converges toward the saturation temperature during discharge.